// Copyright (c) 2016 The btcsuite developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.

package main

import (
	"container/heap"
	"math/rand"
	"testing"

	"github.com/btcsuite/btcutil"
)

// TestTxFeePrioHeap ensures the priority queue for transaction fees and
// priorities works as expected.
func TestTxFeePrioHeap(t *testing.T) {
	// Create some fake priority items that exercise the expected sort
	// edge conditions.
	testItems := []*txPrioItem{
		{feePerKB: 5678, priority: 3},
		{feePerKB: 5678, priority: 1},
		{feePerKB: 5678, priority: 1}, // Duplicate fee and prio
		{feePerKB: 5678, priority: 5},
		{feePerKB: 5678, priority: 2},
		{feePerKB: 1234, priority: 3},
		{feePerKB: 1234, priority: 1},
		{feePerKB: 1234, priority: 5},
		{feePerKB: 1234, priority: 5}, // Duplicate fee and prio
		{feePerKB: 1234, priority: 2},
		{feePerKB: 10000, priority: 0}, // Higher fee, smaller prio
		{feePerKB: 0, priority: 10000}, // Higher prio, lower fee
	}

	// Add random data in addition to the edge conditions already manually
	// specified.
	randSeed := rand.Int63()
	defer func() {
		if t.Failed() {
			t.Logf("Random numbers using seed: %v", randSeed)
		}
	}()
	prng := rand.New(rand.NewSource(randSeed))
	for i := 0; i < 1000; i++ {
		testItems = append(testItems, &txPrioItem{
			feePerKB: int64(prng.Float64() * btcutil.SatoshiPerBitcoin),
			priority: prng.Float64() * 100,
		})
	}

	// Test sorting by fee per KB then priority.
	var highest *txPrioItem
	priorityQueue := newTxPriorityQueue(len(testItems), true)
	for i := 0; i < len(testItems); i++ {
		prioItem := testItems[i]
		if highest == nil {
			highest = prioItem
		}
		if prioItem.feePerKB >= highest.feePerKB &&
			prioItem.priority > highest.priority {

			highest = prioItem
		}
		heap.Push(priorityQueue, prioItem)
	}

	for i := 0; i < len(testItems); i++ {
		prioItem := heap.Pop(priorityQueue).(*txPrioItem)
		if prioItem.feePerKB >= highest.feePerKB &&
			prioItem.priority > highest.priority {

			t.Fatalf("fee sort: item (fee per KB: %v, "+
				"priority: %v) higher than than prev "+
				"(fee per KB: %v, priority %v)",
				prioItem.feePerKB, prioItem.priority,
				highest.feePerKB, highest.priority)
		}
		highest = prioItem
	}

	// Test sorting by priority then fee per KB.
	highest = nil
	priorityQueue = newTxPriorityQueue(len(testItems), false)
	for i := 0; i < len(testItems); i++ {
		prioItem := testItems[i]
		if highest == nil {
			highest = prioItem
		}
		if prioItem.priority >= highest.priority &&
			prioItem.feePerKB > highest.feePerKB {

			highest = prioItem
		}
		heap.Push(priorityQueue, prioItem)
	}

	for i := 0; i < len(testItems); i++ {
		prioItem := heap.Pop(priorityQueue).(*txPrioItem)
		if prioItem.priority >= highest.priority &&
			prioItem.feePerKB > highest.feePerKB {

			t.Fatalf("priority sort: item (fee per KB: %v, "+
				"priority: %v) higher than than prev "+
				"(fee per KB: %v, priority %v)",
				prioItem.feePerKB, prioItem.priority,
				highest.feePerKB, highest.priority)
		}
		highest = prioItem
	}
}